July 19, 2010

“It’s synthetic sandstone. All that’s happening is crystals are growing
around sand grains.”

The way in which Professor Ginger Dosier describes her innovative process
that has recently won the Metropolis
“Next Generation” design competition is accurate, but perhaps slightly
over-simplified.

I never ceased to be amazed by friendly bacteria. We may have an
instinctively negative view of our super-abundant microbial colleagues, but many
of them are really helpful, and we’d be in a bad way without them. Take, for
example, the bacteria that munch on natural crude oil in ocean
water or in sand;
take the wondrous critter, bacillus pasteurii, that can turn
sand into sandstone and heal
cracks in concrete. And now here, although appearing under a different
name, is bacillus pasteurii again.

Ginger Dosier is an architect at the American University of Sharjah, in the
United Arab Emirates, but an architect with a difference: she is interested in
designing her own building materials and thereby participating directly in
influencing the performance of a building. She has chosen the most basic of
building materials, the brick; as she comments, “Bricks are so humble, they are
the lowest common denominator in architecture. Bricks were designed around our
hands; one is used for holding the brick and the other for the trowel. I wanted
something that would slip right into the system and the entire construction
system would not have to be redefined.” And what she has done is potentially of
huge importance, because bricks may be humble, but their manufacture consumes
large amounts of energy and creates more atmospheric pollution than the entire
aviation industry. A standard brick must be fired in a kiln at temperatures
greater than 1000 degrees centigrade; making a couple of bricks generates more
than a kilogram of carbon dioxide – and it’s estimated that perhaps 1.2 trillion
bricks are manufactured around the world every year. Dosier’s solution is don’t
bake the brick, grow it.

And this is where our old friend, bacillus pasteurii plays the
leading role. Although the reports of the brick-making process describe the
bacteria used as sporosarcina pasteurii, it would seem that this is just
an alternative (stage?) name for bacillus pasteurii - why the
microbiologists can’t make up their minds is beyond me, but there we
are. Bacillus pasteurii, if treated right, produces calcite
that can glue sand grains together (or mend concrete, for that matter); the
process is referred to as microbial-induced calcite precipitation, or MICP.
Treating the bacteria right requires feeding them which is where the urine comes
in – urea [(NH2)2CO] can be made synthetically or
from urine, and provides nutrition for the bacteria. Water is also necessary, as
is calcium chloride.

The process for making a brick is relatively
straightforward: put dry sand into a mould, add the cultured bacteria, water,
urea, and calcium chloride, and wait for about a week – other than the 37
degrees centigrade at which the bacteria must be prepared, no heating is
required. But it took Dosier two years to find the right proportions of
materials, the right microbes, and the right chemistry, and her eventual success
was another example of laboratory serendipity:

Then one afternoon, she threw together a bunch of scraps from some old,
ill-fated tests, for kicks. Practically forgetting about it, she revisited
experiment No. 112 a week later, only to discover that the medium had
transformed into a “baby brick,” as she tells it, a
four-by-two-by-one-centimeter proof of concept. “I was shocked to find that it
had worked,” she says, “and glad that I took detailed lab notes.” The magic
formula was in allowing the right concentration of bacteria to fester just long
enough.

Currently, her bricks are small - about 3cm long, 1.5cm wide and a centimetre
deep – but she’s working on scaling up. And scaling up to any kind of commercial
mass production process is yet another, hardly trivial, step. But the potential
is huge. Dosier contemplates the ability to program a brick’s exact composition
and then “ fabricate it layer by layer on a 3-D printer. The technology poses
countless design possibilities. Ball-shaped bricks: Why not?” (Metropolis).

But, as usual, it’s still not quite that simple:

Microbial-induced calcite precipitation spews tremendous amounts of ammonia,
as scientists affiliated with Delft University of Technology, in the
Netherlands, discovered recently when they tried the chemical process on
contaminated sand and soil. “High ammonia concentrations result in environmental
eutrophication and eventually, via microbial conversion to nitrate, the
poisoning of groundwater,” the Delft researcher Henk Jonkers writes in an
e-mail. If the bacteria continues to convert ammonia to nitrous oxide, he adds,
it can produce a greenhouse gas 320 times more powerful than CO2.

Dosier is thinking about emissions capture in the manufacturing process,
another complex and multi-disciplinary challenge, but she’s up for it: having
come so far as an architect learning and working in different worlds, she
deserves to succeed.

Comments

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It is always fascinating to learn how the microbial world;in spite of the real moratl dangers some species may pose to other lifeforms;that something so beyond our everyday concerns and many times dis-regarded as mundane or ugly is actually the vital support system that has enabled life to evolve and persist on this planet and probably elsewhere in the universe.

As a fuel source(algae)and in other ways microbial species may turn out to be the integral components of a sustainable society. From my understanding of ecology, there is nothing truly irrelevant or "inferior" in nature and the smallest part of it can have enormous consequences for the whole system. It is sad that our species(some of us at least)has only recently realized these vital interconnections as we increasingly exterminate or absuse and misuse other species and the earth's support systems at our own peril.

Last time I looked Ammonia was a valuable industrial feedstock. The Ammonia production might pay for the entire process, if not at least for the raw materials.

Approximately 83% (as of 2004) of ammonia is used as fertilizers either as its salts or as solutions. Consuming more than 1% of all man-made power, the production of ammonia is a significant component of the world energy budget. - more of this at Wikipedia http://en.wikipedia.org/wiki/Ammonia#Uses

Last time I looked Ammonia was a valuable industrial feedstock. The generated ammonia, liberated no doubt from the urea, could be used to directly produce more urea on site, to feed back in to the process.

Approximately 83% (as of 2004) of ammonia is used as fertilizers either as its salts or as solutions. Consuming more than 1% of all man-made power, the production of ammonia is a significant component of the world energy budget. - more of this at Wikipedia http://en.wikipedia.org/wiki/Ammonia#Uses

It would seem that he is also working on bacterial clean-up of contaminated materials, sand and soils, and that this is the origin of his comment (only cited as an e-mail communication) on the bricks project. I would assume that the nitrate remains in the brick and the ammonia is given off as a gas.

Another concern.
A major source of calcium is calcium carbonate, which comes from
organisms that have sequestered C02 by way of carbonic acid formation (sea shells and a lot of microorganisms). An obvious way to get CaCl2 would be 2HCl+ CaC03= CaCl2 + H2O + CO2. Unfortunately this would release a lot of CO2 a known green house gas.
However, a lot of CaCl2 may already be made at the bottom of fracking wells which have
been boosted by injecting HCL to promote the above reaction and the CO2 contributes to
cracking pressures.